The mechanical switches are devices used to connect and disconnect a load from an electric power source and are based on applying an external force moving several moving contacts with respect to other fixed contacts, such that when the circuit is going to close, the moving contacts come into contact with the fixed contacts, electrically connecting a load and an energy source, and thereby allowing current circulation.
The opposite process corresponds to the movement of the moving contacts with respect to the fixed contacts, such that these moving contacts move away from the fixed contacts, making the circuit open and therefore interrupting current circulation.
Switches with a different type of movement of its moving parts, either with linear, rotational or helicoidal movement, are known. European patent application EP2,667,394A1 describes an example of a switch with linear movement of the moving contacts. Spanish utility model ES1116655U describes a rotating switch, and European patent application EP2,866,244A1 describes a helicoidal switch.
During transitory opening and closing operations, electrical arcs or voltaic arcs are formed in the contact areas between the moving and fixed contacts. Electrical arcs are known to cause many problems because the heat generated during the occurrence of an electrical arc is highly destructive. Some of these problems are: deterioration of the materials of the switch, malfunctions and/or complete or partial destruction of electrical installations, including injuries to people caused by burns or injuries of another type.
The problems in quenching electrical arcs are particularly notable in direct current interruption, because unlike alternating current, there is no zero-crossing, such that electrical arcs must be eliminated as quickly as possible by means of deionizing the medium and increasing dielectric resistance.
One of the techniques known for increasing efficacy in quenching an electrical arc specifically in the case of DC switches, is the use of a blow-out with a magnetic field generated by permanent magnets.
The technique currently used to produce the magnetic blow-out is to place several permanent magnets in a fixed position such that they drive the electrical arc as quickly as possible to a quenching area, such as deionizing chambers, elongation partitions, etc.
Since the permanent magnets are placed in a fixed position, the generated magnetic field always remains stationary, so in order for the magnetic field to reach the entire area in which the arc extends, several magnets must be used or polar expansions must be added to increase the surface of the magnetic field depending on the length of the path between fixed and moving contacts.
Spanish utility model ES1116655U shows an example of these magnetic blow-out techniques using several permanent magnets installed in a fixed position of the switch.
Since several magnets and polar expanders are required, these conventional techniques involve an increase in the material used, as well as an increase in the volume of the switch for housing the magnets near the area where the electrical arc occurs.
Generally, in the known techniques, the magnets are placed in an intermediate position of the maximum path between the fixed contact and the moving contact, so the magnetic field interferes with the electrical arc once the arc has already been generated, which limits the arc quenching capacity.